1. Field of the Invention
The invention relates to methods for decomposing undesired organic hydroperoxides in liquid solutions and particularly relates to such decompositions which are catalytically promoted.
2. Other Methods in the Field
Organic hydroperoxides are useful materials, particularly as reactants in epoxidations. However, peroxides can also be very troublesome when present as undesirable components (by-products or leftover reactants) in ultimate product streams. For example, in techniques for oxidizing alkanes such as isobutane to give the corresponding alcohol, such as tertiary butyl alcohol for example, tertiary butyl hydroperoxide is also formed as an undesirable by-product. If the t-butyl alcohol is used as an anti-knock, anti-icing additive in gasoline, the t-butyl hydroperoxide must somehow be eliminated as it has an octane degrading effect.
Similarly, in methods for reacting olefins with organic hydroperoxides, there is usually some unreacted hydroperoxide remaining in the product effluent. Typically in such processes, large amounts of the alcohol corresponding to the hydroperoxide are also produced. If this alcohol is to be used in an application that is sensitive to the presence of even small amounts of residual hydroperoxide, as in the gasoline anti-knock, anti-icing additive noted above, the hydroperoxide must in some way be removed.
One technique for removing small quantities of hydroperoxide involves distilling off the hydroperoxide. This technique can be dangerous if it involves concentrating an unstable hydroperoxide. Molecular sieves are known to be effective in the removal of peroxides from contaminated ethers as revealed in D. R. Burfield, "Deperoxidation of Ethers. A Novel Application of Self-Indicating Molecular Sieves," J. Org. Chem., 1982, Vol. 47, pp 3821-3824.
If the problem is one of removing hydroperoxide from a solution of its corresponding alcohol, the typical approach is to decompose or convert the hydroperoxide to the alcohol within the solution. One method of conducting this hydroperoxide decomposition is to treat the contaminated solution with high temperature. U.S. Pat. No. 3,474,151 to Grane teaches that hydroperoxides and peroxides contaminating t-butyl alcohol (TBA) product may be decomposed by subjecting the product to a temperature of from 375.degree. F. to 475.degree. F. for from 1 to 10 minutes. See also U.S. Pat. No. 4,294,999 to Grane, et al. (preferably 400.degree.-450.degree. F. for 5-9 minutes); U.S. Pat. No. 4,296,262 to Grane, et al. (280.degree. F. for 10 hours) and U.S. Pat. No. 4,296,263 to Worrell (340.degree. F. for 90 minutes).
Undesirable hydroperoxides have also been catalytically decomposed. Numerous acidic catalysts or soluble metal catalysts have been employed. Typically the catalysts or reactants employed are acids or ionized metal compounds in solution. The mechanism for acid and ionized metal-induced decomposition of hydroperoxides is discussed in Tobolsky, et al., Organic Peroxides, New York: Interscience, 1954, pp 57-122, and Davies, Organic Peroxides, London: Butterworths, 1961, pp 174-192.
It has also been taught that metals and compounds of metals of Groups IV-A, V-A or VI-A of the Periodic Chart, with the exception of chromium, catalyze the conversion of alkyenyl hydroperoxides to epoxy alcohols as taught in U.S. Pat. No. 3,505,360 to Allison, et al. Further, U.S. Pat. No. 4,059,598 to Coyle demonstrates the decomposition of residual hydroperoxides by contacting the product mixture with a heterogeneous cobalt oxide catalyst which may also contain copper oxide as a promoter. However, as will be shown, cobalt oxide, while it may be heterogeneous, is somewhat soluble in the product mixture. This result is undesirable because it diminishes the amount of available catalyst and because it futher contaminates the product with cobalt.
Therefore, an object of the invention is to provide a technique for organic hydroperoxide decomposition that does not involve a catalyst soluble to any measurable extent.